VulnerabilityPublished 11 Feb 2025Updated 13 Feb 2026

CVE-2025-21259: Microsoft Outlook for Android · User Interface (UI) Misrepresentation of Critical Information

Affects Microsoft Outlook for AndroidSource CVE Database V5

Not known to be exploited · CVSS 5.3 Medium.

Data as of 26 Oct 2026, 09:08 UTC

CVSS 3.1 base score

5.3Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 1.1% chance of exploitation in 30 days – higher than 66% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N/E:U/RL:O/RC:C

Base metrics

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: Low
Availability: None

Temporal metrics

Exploit Code Maturity: Unproven
Remediation Level: Official Fix
Report Confidence: Confirmed

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on the impacted component.
Availability: None: There is no impact to availability within the impacted component.
Exploit Code Maturity: Unproven: No exploit code is available, or an exploit is theoretical.
Remediation Level: Official Fix: A complete vendor solution is available. Either the vendor has issued an official patch, or an upgrade is available.
Report Confidence: Confirmed: Detailed reports exist, or functional reproduction is possible (functional exploits may provide this). Source code is available to independently verify the assertions of the research, or the author or vendor of the affected code has confirmed the presence of the vulnerability.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 11 Feb 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Affected software

Product	Affected	Fixed in
Microsoft Microsoft Outlook for Android	Affected =1.0	Fixed in–

AI-suggested

1. Immediately audit and inventory all devices running Microsoft Outlook for Android version 1.0 to identify vulnerable endpoints. 2. Enforce policies to upgrade Outlook for Android to the latest available version as soon as patches are released by Microsoft. 3. Until patches are available, restrict or discourage the use of Outlook for Android on devices handling sensitive or regulated data. 4. Increase user awareness training focusing on recognizing spoofed UI elements and verifying sender authenticity through alternative channels. 5. Implement multi-factor authentication (MFA) to reduce the impact of credential theft resulting from phishing. 6. Deploy advanced email security gateways with anti-phishing capabilities to detect and block suspicious emails targeting mobile users. 7. Monitor network traffic and logs for unusual patterns indicative of exploitation attempts. 8. Coordinate with Microsoft support for updates and advisories related to this vulnerability. 9. Consider deploying mobile device management (MDM) solutions to enforce app version controls and security policies. 10. Establish incident response procedures specifically addressing UI spoofing and phishing scenarios on mobile platforms.

Description

Microsoft Outlook Spoofing Vulnerability

Impact

For European organizations, this vulnerability poses a risk primarily to the integrity of email communications on mobile devices using Outlook for Android. Attackers could exploit the UI spoofing to conduct sophisticated phishing or social engineering attacks, potentially leading to credential theft, unauthorized access, or malware deployment. Since the vulnerability does not affect confidentiality or availability directly, the immediate technical damage may be limited, but the downstream effects of successful deception can be significant. Organizations with large mobile workforces, especially those relying on Android devices and Microsoft Outlook, are at higher risk. The threat could undermine trust in email communications and complicate incident response. Regulatory environments in Europe, such as GDPR, may impose additional compliance risks if phishing leads to data breaches. The lack of known exploits reduces immediate urgency but does not eliminate the threat, as attackers may develop exploits once details become public.

CWE-451User Interface (UI) Misrepresentation of Critical Information (opens in a new tab)
Class weaknessOWASP Top 10 A06:2025: Insecure Design (opens in a new tab)
The user interface (UI) does not properly represent critical information to the user, allowing the information - or its source - to be obscured or spoofed. This is often a component in phishing attacks.
Implementation · Input Validation
Perform data validation (e.g. syntax, length, etc.) before interpreting the data.
Architecture and Design · Output Encoding
Create a strategy for presenting information, and plan for how to display unusual characters.
OWASP Cheat Sheets
Secure Design Principles (opens in a new tab)
Attack patterns
Spear Phishing (opens in a new tab)
Mobile Phishing (opens in a new tab)
Phishing (opens in a new tab)
Resource Location Spoofing (opens in a new tab)
Action Spoofing (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

msrc.microsoft.com/update-guide/vulnerability/CVE-2025-21259 (opens in a new tab)

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 14 Feb 2026, 08:41 UTC

WeaknessesCWE-451

Technical details

References

Community reviews

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